Chemotactic Nanorobot Tumor Homing

A swarm of medical nanorobots swims down a blood-vessel segment toward a tumor using run-and-tumble chemotaxis — the same biased-random-walk strategy bacteria use to climb a chemical gradient without ever sensing its direction. Each robot only measures whether the local chemoattractant concentration is rising or falling while it swims, extending straight runs during a rise and tumbling to a fresh random heading during a fall, so the swarm nets a statistical drift toward the tumor purely from that temporal bias. Tune the gradient's reach, the swarm's chemotactic sensitivity, its population and the thermal/flow noise it swims through, then watch live readouts track how many robots dock and release their drug payload, how long that takes, and the swarm's net drift speed.